Fabric formed from yarns which have a chemically induced configurational memory



Jl1l|y 1956 E. H. PHTTMAN 3,259,452

FABRIC FORMED FROM YARNS WHICH HAVE A CHEMICALLY INDUCED CONFIGURATIQNAL MEMORY Filed Oct. 15: 3.962

package of we? cross-linked cellulosic yarn having intent crimp and which assumes a poflerned,crimpe d appearance when we? out in water in on umensioned sia'ie crimp-developed celluiosic yarn wer cross-linked wbil in aun'ifofm c onvoluted configuration wef cross-linked cellu losic'yq textured fabric knit from wet cross-linked cel lulosic yarn of FlG.-l' and then we) out INVENTOR.

EDGAR HENRY PITTMAN IVATTORNEY United States Patent 3,259,452 FABRIC FORMED FROM YARNS WHICH HAVE A CHEMICALLY INDUCED CONFIGTEONAL MEMORY Edgar Henry Pittman, Spartanburg, S.C., assignor to Deering Milliken Research Corporation, Spartanbnrg, S.C., a corporation of Delaware Filed Oct. 15, 1962, Ser. No. 230,439 8 Claims. ((18-116) This invention relates to novel cross-linked cellulosic yarn in package form, to a process for the production thereof and to fabrics knit from such yarns.

It is desirable from a styling point of view to have cellulosic, e.g., cotton or rayon, yarns which will produce bulked and textured effects when formed into fabric. However, there are relatively few means of producing such yarns. One of the oldest techniques is'to apply a very high twist to the yarn to produce crepe yarns. However, the lively nature and the crimped condition of the yarn produces problems in knit-ting and Weaving. A more recent technique is to ply a cellulosic yarn with a textured thermoplastic yarn so that the thermoplastic component provides the textured quality to the plied yarn. This technique requires a substantial proportion of the thermoplastic component and thus reduces the desirable qualities of an all cellulosic yarn. The added plying step and the special weaving or knitting procedures necessary due to its bulked and elastic nature are also 'a deterrent to its widespread use. Other possibilties which might be used would be to cross-link the cellulosic yarn in a dry and convoluted state, employing a typical resin treatment. However, problems are presented in knitting or weaving such a crimped yarn, but more important the tensions employed in knitting or weaving remove much of the convolutions in the yarn, which are not recovered when the tension is removed, so that a slack, relatively uninteresting fabric results. Also, garments formed from such yarns tend to become baggy and distorted on wearing as a result of repeated washings. One might substitute a wet cross-linking treatment for the resin treatment, e.g., employing a stuffing box procedure, so that the yarn is in a convoluted state during the wet cross-linking. This produces a yarn which has a conventional, i.e., uncrosslinked, appearance after winding under tension onto a package and thus can be knit readily. However, when a fabric knit from such a yarn is Wet out to develop crimp, the texture produced is not sufliciently pronounced and of a character which would gain wide acceptance commercially. Although fabrics knit from such wet cross-linked yarn have a bulkier, softer quality than the corresponding fabric knit from conventional cellulosic yarn, stitch clarity is still retained to an undesirable degree so that a novel crepe, boucle or similar textured effect is not obtained. The apparent reason for this is that the primary crimp produced by the stuffing box, i.e., the crimp resulting from compressing the yarn, is much too small and indistinct to produce any significant texture in the fabric and the secondary crimp, i.e., the crimp produced by looping and twisting the yarn in the stuffing box, is of such a coarse, irregular, loopy and random nature that much of it phases into the fabric stitch.

It has now been found that a highly desirable and pro nounced boucle or crepe effect can be obtained in fabrics formed from a wet cross-linked yarn treated as described.

herein when a regular crimp pattern is present in a latent form at the time of fabric construction. Stitch clarity is minimized so that a distinct textured and random surface effect is obtained, a highly desirable result from a styling point of View.

According to this invention, these desirable effects are obtained by knitting fabric from a package of cross-linked cellulosic yarn having relatively little dry configurational memory so that the yarn, when removed from the package, has a conventional linear, uncrirriped appearance while in a dry, untensioned state, but which has substantial wet contigurational memory so that when wet out the yarn assumes a crimp having a substantially nonlooped configuration characterized by a regular uniform pattern containing between about 2.5 and about 20, preferably 3.5 to 12, crimps per linear inch of yarn in the wet, untensioned state. Such novel yarn packages are obtained by a process which comprises the steps of placing a cellulosic yarn having relatively little dry or wet configurational memory into a convoluted configuration having a reg ular, uniform pattern with between about 2.5 and 20 convolutions per linear inch of yarn, wet cross-linking the yarn under conditions such that substantial wet but relatively little dry configurational memory is imparted thereto while the yarn is in this convoluted configuration, drying the cross-linked yarn and forming the dried yarn into a package under conventional tension.

The starting yarns employed in the process of this invention are the all cellulosic y-arns having relatively little configurational memory, i.e., those having the properties of untreated cellulosics, e.g., cotton, ordinary and Polynosic rayons and linen. The yarns can be singles or plied, spun staple or continuous multifilament, or mixtures thereof. Preferred are the singles and plied spun cotton and rayon yarns of between-about 5s and s and more preferably between about 5s and 60s total count. Singles are most preferred.

These yarns are placed into a convoluted configuration of a regular uniform pattern which provides between about 2.5 and 20 convolutions per linear inch of yarn. The nature of the convolutions must be such that substantial torque is not imparted to the yarn, because if a torque is imparted to the yarn, this will ma-inifest itself by urging the yarn to assume a looped configuration when relaxed in the wet state. Such a patterned convoluted configuration is most conveniently achieved by knitting the yarn with a tight stitch, e.g., between about 10 and 40 wales and 6 and 40 courses per inch, preferably between about 15 and 30 wales and 12 and 30 courses. It is preferred in the cross-linking step that the stitch pattern is identical from Wale to Wale and course to course. so that a constant pattern is subsequently imparted to the Wet cross-linked yarn, e.g., a simple jersey stitch. To prevent phasing of the crimps in the wet cross-linked yarn with the stitch of the fabric when the yarn is subsequently again knitted into fabric, it is desirable to employ a stitch pattern which is considerably tighter than is conventionally employed in most fabrics. The tubular knitting machines employed for imparting crimp to thermoplastic yarns by the knit, set and unknit method can be employed in this process.

The yarn in the above-described convoluted configuration is then cross-linked under conditions which impart substantial wet, but relatively little dry, configurational memory thereto. This can be achieved according to techniques known in the art by cross-linking the cellulose molecules with a cross-linking agent which is reactive in the presence of substantial amounts of water. To insure that relatively little dry configurationa-l memory is concurrently imparted to the yarn, it is ordinarily necessary to conduct a cross-linking while the yarn contains at least 15% by weight of water, ordinarily about 30-100% or more Water.

Wet cross-linking agents which can be employed include the acid catalyzed wet cross-linking agents, e.g.,

formaldehyde, acetaldehyde, glyoxal, a-hydroxyadipaldew Patented July 5, 1966 cross-linking agents, e.g., diepoxybutane, diglycidyl ether of ethylene glycol, of propylene glycol and of diethylene glycol, triethylene glycol and other polyalkylene ether glycols, the diglycidyl ether of bis-phenol A, the diand tri-glycidyl ethers of glycerol, and compounds having an a-halohydrin, e.g., chlorohydrin or bromohydrin, in place of one or more of the epoxy groups, and compounds having a halogen atom, e.g., chlorine or bromine, or to an epoxy group or halohydrin group, e.g., epichlorohydrin, epibromohydrin, 2-methyl epichlorohydrin, 1,2-dichloropropanol, 1,3-dichloropropanol-2, and bis-(l-chloro-2- hydroxy-n-propoxy) ethane. Other alkaline catalyzed wet cross-linking agents include the activated divinyl compounds, e.g., divinyl sulfone, divinyl sulfoxide, bis-(vinyl sulfonyl) methane, divinyl ketone, and octa-1,7-diene- 3,6-dione, and compounds containing two or more activated sulfato and phosphato esters and their alkali-metal salts, e.g., disodium 'bis-sulfatoethyl sulfone, disodium bis-sulfatoethyl sulfoxide, disodium bis-thiosulfatoethyl sulfone, and similarly activate-d quaternary ammonium compounds.

The catalysts used to catalyze the above compounds are known in the art. For example, the strong mineral acids, including hydrochloric, sulfuric and phosphoric acids, are ordinarily used to catalyze the acid catalyzed wet cross-linking agents. Similarly, the alkali-metal hydroxides, e.g., sodium hydroxide and potassium hydroxide, are ordinarily used to catalyze the alkaline catalyzed wet cross-linking agents, although other strong bases, e.g., those having a pH of or higher as a 1% aqueous solution, including sodium silicate, sodium sulfide, dimethylphenyl ammonium hydroxide, tetramethyl ammonium hydroxide and others, can be used.

The amounts of cross-linking agent, catalyst and moisture which should be present during the wet cross-linking agent depend, to a certain extent, upon the selected crosslinking agent and catalyst. These techniques are now well known in the art. See, e.g., US. Patents 2,524,399; 2,985,501; Guthrie, Textile Research Journal, 29, 834, October, 1959.

When employing an alkaline catalyzed wet cross-linking agent, the reaction can conveniently be achieved by impregnating the fabric with an aqueous solution of the selected catalyst of the selected concentration and then contacting the impregnated fabric with the cross-linking agent. The yarn is then maintained at the proper temperature, e.g., -90 C., and for the proper time, e.g., a few minutes to several hours, until the desired cross-linking reaction has taken place. The yarn can then be scoured to remove excess cross-linking reagent, catalyst and/ or reaction by-products and dried.

The yarn is then removed from its highly convoluted configuration and wound into a yarn package, employing conventional winding procedures. The yarn can be cone wound or flat wound into a cheese, e.g., on a Barber- Coleman or Universal winder to packages suitable for dyeing, bleaching, warping, knitting, rewinding or sales. Obviously, the wet yarn can be taken up onto a package before drying, but it is ordinarily more convenient to dry the yarn first. The yarn can then be formed into Woven or preferably knitted fabric using conventional techniques, but forming fabric of somewhat looser than ordinary construction so as to permit the yarn to contract into its convoluted configuration when the fabric is wet out.

The present invention is illustrated in the accompanying attached drawings in which FIG. 1 is a schematic view of a package of yarn according to this invention wet cross-linked as described herein;

FIG. 2 is a highly enlarged view of a length of cellulosic yarn forming the novel packages of yarns of this invention, in its convoluted configuration;

FIG. 3 is a highly enlarged view of a cellulosic yarn Wet cross-linked in a stuffer box;

FIG. 4 is a plan view of a face of a knitted fabric of this invention knit from a package of yarn of the type shown in FIG. 1.

FIG. 1 illustrates the fact that the novel packages 1 of yarns of this invention have a conventonal appearance and, except for the typcal loss of strength due to the crosslinking, the yarn on the package has substantially the same properties and knitting charatceristics as a conventional cellulosic yarn until wet out. This is because the lack of dry configurational memory in the yarn enables the tension imparted to the yarn in winding it into a package to temporarily remove its convolutions. However, the yarn 2 has latent crimp and will return to its convoluted state when wet out in an untensioned condition. The cellulosic yarn 2 shown in FIG. 2 illustrates the fact that the yarns forming the yarn packages of this invention, when wet out in an untensioned state, will assume a convoluted condition which has a regular uniform pattern which is substantially free from loops or coils and which substantially reproduces the convolutional pattern of the yarn when it was cross-linked. While each convolution may not be identical to every other convolution, particularly if the convolutions are formed by knitting into a rib or otherwise patterned fabric rather than a simple jersey fabric, the over-all effect of the convolutions is one of uniformity. FIG. 3 illustrates the different type of yarn 3 that is produced when cellulosic yarn is wet cross-linked while in a convoluted configuration produced by a stuffer box. Not only is the yarn flattened to an undesirable degree, but the readily visible crimps, i.e., the secondary crimp, are a highly loopy and random type which does not produce a good textured effect when knit into fabric. The primary crimp produced is so small and so dense that it is scarely visible and contributes little to the bulking characteristic of the yarn. Although. fabric knit from yarn of the type shown in FIG. 3 has an appearance which is softer and more Wool-like than fabric knit from conventional cellulosic yarns, it does not produce the desirable bulked and textured effect that is obtained employing yarns produced according to the process of this invention.

FIG. 4 illustrates the highly textured effect obtainable in fabrics 4 knit from the wet cross-linked cellulosic yarns 2 taken from the yarn packages 1 of this invention and then wet out. As can be seen from the drawing, the stitch pattern is scarcely visible which is a distinctly different effect than is obtained with conventional cellulosic yarns, which produce fabrics having great stitch clarity. This loss of stitch clarity to obtain bulked and textured effects is highly desired in fabric styling and was heretofore obtained only with yarns of a very special construction.

As stated above, the wet cross-linked cellulosic yarn of this invention can be knit into fabric and garments or woven into cloth in the same manner as conventional yarn. To produce fabrics having the desired textured effect, the stitch or weave should be relatively loose so as to permit the yarn to contract into a convoluted configuration when the fabric is wet out. The stitch or weave should be such that the latent convolutions in the yarn, when they are developed in the wetting out step, will not phase into the stitch construction of the fabric. Thus, if the yarn has 2.5 to 20, or the preferred 3.5 to 12 latent crimps per linear inch of yarn, fabric knit from such yarn should impart a lesser number, preferably about 25% to about 75% of this number, of fabric stitches per linear inch of yarn. Best results are obtained with yarn having about 5 to about 8 latent crimps per linear inch of yarn when it is knitted into fabric having about 40-75% of this number of fabric stitches per linear inch of yarn.

The conversion of the latent crimp into visible crimp is achieved by wetting out the fabric in water or steaming. Agitation is helpful in developing the crimp as is the use of a conventional detergent in the water. Hot or cold water can be used to develop the crimp.

Because the yarn has little dry configurational memory, it would be expected that when the convolutions in the yarn are developed in fabric form by wetting out the fabric, the resulting fabric would have little tendency to retain these crimps after it is dried out and worn or hung. Surprisingly, the crepe or boucle effect produced in the fabric is very stable in use. Moreover, what little loss of crimp occurs in use is readily and completely restored by washing the fabric. Garments formed from such yarns display outstanding dimensional stability so that little, if any, bagginess and other distortions occur on wearing and repeated hand or machine launderings, a result completely different from that obtained with yarns treated by a conventional resin treatment.

The following examples are illustrative of the process and products of this invention but are not to be construed as limiting. 1

Example I Knit 2 ply 40s mercerized cotton yarn, into a tubular jersey fabric having about 30 courses per inch (fabric taut lengthwise) using a 300 needle 3.75 inch diameter knitting machine.

Pad the resultant fabric with an aqueous solution of 4% NaOH and 1% Mercerol G. V. wetting agent and squeeze through rolls to about an 80% pickup. Preferential NaOH pickup from the solution provides about 4% NaOH on the fabric, calculated on its dry weight. With a slowly rotating applicator roll apply about calculated on the dry weight of the fabric, of epichlorohydrin. Roll the fabric into a roll, seal in a polyethylene wrapper and age for about 16 hours at about 45 C. Wash the fabric thoroughly, employing about 2% Arquad 2HT cationic softener in the last rinse. Dry the fabric and unravel the dry fabric, reeling the yarn onto a yarn cone to provide a package of yarn. Employ enough winding tension s0 thatthe yarn presents the appearance of conventional yarn on the package. After about one-half hour, yarn removed from the package has the appearance of conventional yarn in a relaxed dry state but, because of its latent crimp, immediately assumes a crimped configuration, with about 6 crimps per linear inch of yarn both in a fully relaxed wet state and after drying in a relaxed state. If the yarn is dried while in the relaxed crimped state, the crimped configuration is retained but is temporarily removed in the same way as described above if the yarn is maintained under tension for about a half hour or longer, e.g., by winding into a package under conventional tensions.

Example ll Example 111 Knit s singles spun rayon yarn having about 11 t.p.i. S twist into fabric on a 220 needle 3.75 inch diameter tubular knitting machine with 26 courses per inch. Immerse the thus obtained tubular fabric in 3% aqueous NaOH containing 1% Mercerol G. V. wetting agent for two minutes. Place the fabric in a polyethylene bag, add about 25%, calculated on the dry weight of the fabric, of epichlorohydrin, seal the bag and place in an oven heated to about 55 C. for two hours. Wash the fabric thoroughly, adding of Alaquat H226 cationic softener to the last wash. Dry and unknit the fabric, winding the yarn on a cone, with conventional tension to form a yarn package. A 40 yd. length of this yarn in 27" long skein form, weighted with a 0.68 gram weight, shrinks to 13.5" when suspended in water at 60 C. (The starting yarn shrinks to 25.5" in this test.) This yarn dried in a tensionless state contains about '6 crimps per linear inch of yarn.

Centrifuge to about 70% wet uptake..

6 Example IV Impregnate a knit cotton fabric described in Example I with 1% aqueous NaOH containing 1% Mercerol G. V. wetting agent. Squeeze to about a 70% pickup. Apply about 15%, calculated on the weight of the dry fabric, of divinyl sulfone to the wet fabric by means of an applicator roll. Seal in a polyethylene bag and heat in an oven at 55 C. for about 15 minutes. Wash the fabric thoroughly, including a weak acid scour, and dry. Unravel the fabric and wind the yarn onto a yarn cone with sulficient tension to provide a compact, rigid package. Yarn removed from such a package has a conventional linear appearance in the dry state, but when wet out in an untensioned state develops about 6 crimps, of the type shown in FIG. 2, per linear inch of yarn.

Example V Knit 2 ends of the wet cross-linked cotton yarn obtained in the manner described in Example I on a Dubied V-bed 12-cut machine, using all needles in the back bed, 2-needles in l-needle out in the front bed with a stitch setting which provides about 18 courses per inch in the relaxed fabric. This provides about 4.2 stitches per linear inch of yarn. A rather loose (18 courses, l8 wales per inch face, 9 wales/in. back) but otherwise conventional appearing fabric is obtained which, when immersed in water, is converted into a novelty fabric having an interesting boucle effect with about 26 courses and 13 wales (face), 6.5 wales (back) per inch. This effect is retained when the fabric is tumble dried. When the fabric is formed into a dress or other garment, the garment does not require ironing. The novel boucle effect is retained after repeated wearings and washings. Such a garment has a light feeling to the wearer and has a cool, comfortable quality.

Example VI Follow the procedure of Example V, using 24s singles Wet cross-linked cotton yarn obtained from a package of yarn obtained according to the procedure of Example II, using a l x 1 rib stitch pattern. A pleasing novelty boucle effect fabric is obtained (24 courses, 18 wales per inch), having about 3.3 fabric stitches and about 5.4 crimps per linear inch of yarn, when the fabric is wet out in hot water and dried in a substantially tensionless state. The fabric is considerably bulkier per unit weight than the untreated yarn.

Similarly, using a jersey or a full cardigan stitch pattern produces fabric having 4.2 and 3.3 stitches per linear inch of yarn and 6.0 and 6.9 crimps per linear inch of yarn, respectively, when the fabrics are wet out in hot water and dried.

Example VII Knit 6s spun rayon yarn into a tube on an 84 needle, 3.5 inch diameter knitting machine. Pad the resulting fabric through 3% NaOH containing 1% Mercerol G. V. wetting agent. Squeeze to about a 7080% pickup. Apply about 10% epichlorohydrin, calculated on the weight of the dry fabric. Wind the fabric onto a roll, wrap in polyethylene and maintain for about 18 hours at about 38 C. Wash thoroughly and soften with 0.25% Alaquat H-226 softener. Dry, unknit a-ndconically wind into a package. Yarn removed from the package after a few hours has the appearance of conventional yarn but a 27 inch skein containing 40 yds. of yarn and weighted with a 0.68 g. wt. shrinks in water at 60 C. to 18 inches as it develops about 2.8 convolutions per inch of the type shown in FIG. 3.

Wind the yarn from the package onto quills and weave into a twill construction fabric using a 58 ends per inch 21s cotton yarn warp with 54 picks per inch in the filling. The fabric has a loose and sleazy appearance but, when washed in hot water with gentle agitation, is converted into an attractive 3-dimensional rippledfabric well suited for draperies.

What is claimed is:

1. A textile fabric wherein the cellulosic component of the material from which it is made is a cellulosic yarn whose cellulose molecules are cross-linked so that the yarn has substantial wet but relatively little dry configurational memory, so that the yarn assumes in a wet untensioned state a crimped substantially non-looped configuration having a regular uniform pattern with between about 2.5 and 20 crimps per linear inch of yarn.

2. The textile fabric of claim 1 wherein the cellulosic yarn comprises wet cross-linked rayon.

3. The textile fabric of claim 1 wherein the cellulosic yarn comprises wet cross-linked cotton.

4. The textile fabric of claim 1 wherein the cellulosic yarn has a yar-n count between about 5 and 60 and assumes in a wet untensioned state between about 3.5 and 12 crimps per linear inch.

5. The textile fabric of claim 1 wherein the fabric is knit so as to impart a number of fabric stitches per linear inch of yarn which is less than the number of crimps per linear inch of yarn in a wet untensioned state.

8 6. The textile fabric of claim 5 wherein the number of stitches per inch is between about and 75% of the number of crimps per inch.

7. The textile fabric of claim 6 wherein the yarn is cross-linked cotton of between about 5s and s count. 8. The textile fabric of claim 5 wherein the yarn has between about 3.5 and 12 crimps per linear inch of the yarn and the fabric is knit so as to impart a number of fabric stitches per linear inch of yarn which is between about 40% and of the number of crimps per inch in the yarn.

References Cited by the Examiner UNITED STATES PATENTS 2,789,340 3/1957 Cresswell 2872 2,985,501 5/1961 Gargarine 8--120 FOREIGN PATENTS 1,105,545 7/1955 France.

NORMAN G. TORCHIN, Primary Examiner.

J. CANNON, Assistant Examiner. 

1. A TEXTILE FABRIC WHEREIN THE CELLULOSIC COMPONENT OF THE MATERIAL FROM WHICH IT IS MADE IS A CELLULOSIC YARN WHOSE CELLULOSE MOLECULES ARE CROSS-LINKED SO THAT THE YARN HAS SUBSTANTIAL WET BUT RELATIVELY LITTLE DRY CONFIGURATIONAL MEMORY, SO THAT THE YARN ASSUMES IN A WET UNTENSIONED STATE A CRIMPED SUBSTANTIALLY NON-LOOPED CONFIGURATION HAVING A REGULAR UNIFORM PATTERN WITH BETWEEN ABOUT 2.5 AND 20 CRIMPS PER LINEAR INCH OF YARN. 